Lifting device for containers

ABSTRACT

The invention relates to a lifting device ( 2 ) for containers ( 18 ), especially ISO containers ( 18 ) which can be handled by container handling devices ( 1 ), comprising a drive means for traction means ( 16 ), which is arranged on a supporting frame ( 3 ) in order to raise and lower the container ( 18 ) by means of a load-receiving means arranged on the lower end of the traction means ( 16 ). In order to create a low-volume lifting device for a container handling device, requiring only a small amount of bridging height, the drive means comprises at least one hydraulic cylinder ( 4 ) with a piston and a piston rod ( 5 ) whose longitudinal displacement is converted into a synchronous upward and downward movement of at least two distanced horizontal guiding cross-bars ( 10   a   , 10   b ) which are respectively connected to the upper ends of the traction means ( 16 ), said guiding cross-bars ( 10   a   , 10   b ) being guided on both ends on vertical carriers of the supporting frame ( 3 ).

The invention concerns a lifting device for containers, especially ISOcontainers which can be handled by means of container handling gear,with a drive means for traction means, which is arranged on a supportingframe in order to raise and lower the container by means of aload-receiving means arranged on the lower end of the traction means.

At container ports and in container yards, ISO containers are loaded andunloaded by means of handling gear, especially by means of straddleloaders, straddle carriers and container movers, which are used for theloading and unloading of trucks, railroad cars, trailers, or evenautomated guided vehicles (AGV). The trucks, railroad cars, trailers andautomated guided vehicles are passive transportation vehicles, sincethey cannot themselves pick up and put down the containers beingtransported, whereas straddle loads, straddle carriers and containermovers are active transportation vehicles, i.e., a container beingtransported within the container yard or the container port can also bepicked up and placed down by them.

It is known that container handling equipment have motors on theirchassis, which drive one or more cable winches. The cables of thewinches are guided across several deflection rollers to four fasteningpoints of a load-receiving means in the form of a spreader. By means ofthe motor or motors, the cables are wound and unwound, thereby varyingthe lift height of the spreader. The loading or unloading of a passivetransportation vehicle begins when an ISO container is picked up bymeans of the spreader and lifted by winding up the cables. The containerhandling unit now travels the container above the transport vehicle andsets the container down on its loading surface. The unloading of thetransportation vehicle occurs accordingly in the opposite sequence. Thecontainer handling equipment is likewise used for transport ofcontainers within the container yard and container port, the containerbeing lifted during the transport.

The cable lifting mechanisms used in the container handling equipmentrequire an intensive maintenance, which leads to long down times for thecontainer handling equipment, besides high maintenance costs. At thesame time, the known cable lifting mechanisms are bulky in construction.

The container handling equipment is used for the loading of trucks,railroad cars, trailers, or also automated guided vehicles, on which thecontainers are not stacked one on the other. Consequently, only lowheights of 1.2 m to 3.8 m can be achieved, so that the cable liftingmechanisms can also be smaller in dimension.

The purpose of the invention is therefore to create a low-volume liftingdevice for container handling equipment for a relatively small bridgingheight.

This purpose is accomplished by a lifting device with the features ofclaim 1. Advantageous configurations of the lifting device are indicatedin the subsidiary claims.

The solution entails that the drive means comprises at least onehydraulic cylinder with a piston and a piston rod, whose lengthwisedisplacement is transformed into a synchronous upward and downwardmovement of at least two distanced horizontal guiding cross-bars, whichare connected respectively to the upper ends of the traction means, theguiding cross-bars being guided at both ends on vertical beams of thesupporting frame. The more economical hydraulic cylinder represents amaintenance-friendly drive system for the lifting device, at the sametime ensuring a high carrying capacity with a small footprint. Theguiding of the two ends of the guiding cross-bars further reduces thetwisting of the suspended load-receiving means relative to the supportframe and/or the container. This ensures a torsion-proof and exactorienting of the load-receiving means in relation to the container beingpicked up.

A flat-design lifting device on top of the spreader is achieved bytransforming the transmission of force of the hydraulic cylinder and thelengthwise motion of the piston rod above the container into the upwardand downward movement, which is accomplished by means of angle levers,with two lever arms each, pivoted on the support frame, one lever arm ofone angle lever being connected to a piston rod and the other lever armof said angle lever being connected to a guiding cross-bar.

If the lever arm of an angle lever connected to the piston rod is linkedby means of a rod-shaped coupling element to a lever arm of anotherangle lever, whose other lever arm is connected to the other guidingcross-bar, the corresponding traction means move synchronously to eachother in the vertical direction. At the same time, the use of the anglelevers enables a flat-design lifting device.

A mechanically stable connection is achieved when the guiding cross-barsare each connected by means of a coupling rod to one lever arm.

A tilting of the guiding cross-bars is prevented if the guidingcross-bars are each connected by means of a connecting rod to a leverarm on both sides of the middle of the cross-bars.

The transformation of the lengthwise displacement into the lifting andlowering movement by means of lifting cables which are deflected andfastened to a single piston rod, being connected at the other end atleast indirectly to the guiding cross-bars, wherein the deflection isdone by means of freely turning deflection rollers, enables the use of amaintenance-friendly and more economical hydraulic cylinder in aflat-design construction. An additional synchronization of the liftingcables fastened to a single piston rod is not required.

Preferably the deflection of the lifting cables occurs in the directionvertical to the particular guiding cross-bars by means of a freelyturning deflection roller.

The invention will now be described by means of a drawing. This shows:

FIG. 1, a container handling unit in side view with a lifting deviceusing angle levers,

FIG. 2, a container handling unit in front view of a lifting deviceusing angle levers,

FIG. 3, the lifting device for a container handling unit in aloading/unloading position,

FIG. 4, the lifting device for a container handling unit in a top view,

FIG. 5, the lifting device for a container handling unit using deflectedlifting cables, and

FIG. 6, detail drawings of the lifting device with lifting cables.

FIG. 1 shows a container handling unit 1 with a lifting device 2, havinga support frame 3. Linked to the support frame 3 is a hydraulic cylinder4, whose piston rod 5 is connected to a lever arm 6 of an angle lever 7,which is pivoted about its axis A, located at the apex. The other leverarm 8 is connected via a vertical coupling rod 9 a to a guidingcross-bar 10 a by means of a tie bracket 11 a. To the lever arm 6 of theangle lever 7 is linked a horizontal coupling rod 12, which is connectedat its other end to a lever arm 13 of a second angle lever 14, which islikewise pivoted about its axis B located at the apex. The lever arm 15of this angle lever 14 is likewise connected via a vertical coupling rod9 b to a guiding cross-bar 10 b by means of a tie bracket 11 b. The twovertical coupling rods 9 a, 9 b each engage the upper ends of therespective tie brackets 11 a, 11 b, while at the lower ends of the tiebrackets 11 a, 11 b are arranged additional traction means 16 in theform of chains. Secured to the lower ends of the chains is the spreader17, being the load-receiving means. The horizontal position of thespreader 17 is parallel with the standing surface of the containerhandling unit 1.

The container 18 is situated at low height above the standing surface.The piston rod 5 of the hydraulic cylinder 4 is retracted, so that theguiding cross-bars 10 a, 10 b and consequently the spreader 17 are intheir upper end position. This upper end position is likewise thetransport position for the spreader 17, the lifting device 2, and thecontainer 18. The angle levers 7, 14—as FIG. 1 shows—project onlyslightly above the support frame 3 in the transport position.

FIG. 2 shows the container handling unit 1 in a front view, where acontainer 18 standing on the floor is located in its loading/unloadingposition. The lifting device 2, the guiding cross-bars 10 a, 10 b, andthe spreader 17 are likewise in their loading/unloading position, inorder to pick up (or unload) the container 18. Arranged on either sideof the middle of the cross-bars are a chain, a tie bracket 11 a, acoupling rod 9 a and a lever arm 8 of an angle lever 7. The guidingcross-bar 10 a, thanks to the simultaneous activation of the identicaland rigidly connected angle lever 7, runs parallel to the standingsurface of the container handling unit 1. One notices from the frontview that the embodiment is implemented pairwise (FIG. 4).

FIG. 3 shows the lifting device 2 with the angle levers 7 and 14 in sideview, again in the loading/unloading position. The piston rod 5 of thehydraulic cylinder 4 is almost fully extended. The angle lever 7 isrotated counterclockwise about its pivot axis A relative to itstransport position. As a result, the lever arm 8 and the coupling rod 9a are tilted toward the floor, so that the guiding cross-bar 10 a is inthe loading/unloading position. The horizontal coupling rod 12, linkedto the lever arm 6 of the angle lever 7, causes the angle lever 14 toturn clockwise about its pivot axis B relative to its transportposition. As a result, the lever arm 15 and the coupling rod 9 b aretilted toward the floor, similar to the lever arm 8 and the coupling rod9 a. Accordingly, the second guiding cross-bar 10 b is likewise in thelower position, at the same height as the first guiding cross-bar 10 a.The spreader 17, fastened to the guiding cross-bars 10 a and 10 b bymeans of traction means 16 of equal length, is located in itsloading/unloading position, parallel to the standing surface of thecontainer handling unit 1.

The lowering and lifting of the spreader 17 is accomplished by theextending and retracting of the piston rod 5 of the hydraulic cylinder4. As the piston rod 5 travels, the angle levers 7, 14 turnsynchronously, so that both guiding cross-bars 10 a, 10 b movesynchronously, which entails a vertical movement of the spreader 17,which is always situated in a horizontal plane parallel to the standingsurface of the container handling unit 1.

In the loading/unloading position, the lever arms 8, 15 of the anglelevers 7, 14 project far down and reach into the free space, which isotherwise filled by a container 18 during its transport.

A U-shaped guide rail 20, arranged on the vertical support pillars 19 ofthe support frame 3, guides the ends of the vertically movable guidingcross-bars 10 a, 10 b.

The maximum stroke length of the piston rod 5 of the hydraulic cylinder4 need not correspond to the distance between lowermost and uppermostend position of the spreader 17. Since the lever arms 6, 8 (and 13, 15)of the angle lever 7 (and 14) are of different length, it works in themanner of a slewing gear. Because the driven lever arms 8, 15 of theangle levers 7, 14 are longer than the lever arms 6, 13, the spreaderstroke is larger than the corresponding stroke motion of the piston rod5.

FIG. 4 shows a top view of a lifting device 2. The hydraulic cylinders 4are linked by their end opposite the piston rod 5 to the longitudinalcolumns 21 of the support frame 3, which thus serves to buttress thehydraulic cylinder 4.

The lifting device 2, which comprises the support frame 3, the hydrauliccylinder 4, the piston rod 5, the lever arms 6, 7, 13, 14 of the anglelevers 7, 14, the vertical piston rods 9 a, 9 b and the horizontalcoupling rod 12, are arranged symmetrically to the line of symmetry S.Instead of this pairwise, symmetrical configuration of the hydraulicdrive, a single configuration could also be realized.

In the two longitudinal columns 21 of the support frame 3, turning tubes38, 39 are mounted, the turning tube 38 being able to turn about theaxis A and the turning tube 39 about the axis B. Secured to the turningtube 38 on either side of the line of symmetry S are two identical anglelevers 7, which are rigidly joined together by the turning tube 38.Thus, the two angle levers 7 move synchronously. Similarly, twoidentical angle levers 14 are joined together on the turning tube 39.

The lengthwise movement of the piston rod 5 of the hydraulic cylinder 4displaces the angle lever 7 in a rotary motion, which is transformed bymeans of the coupling rod 9 a into a vertical movement of the guidingcross-bar 10 a. The rotary motion of the angle lever 7 is transmitted bymeans of the horizontal coupling rod 12 to the angle lever 14, and theangle lever 14 in turn transforms its rotary motion by means of thecoupling rod 9 b into a vertical movement of the guiding cross-bar 10 b.This design ensures a synchronous movement of the guiding cross-bars 10a and 10 b, which is transmitted via the traction means 16 to thespreader 17 suspended therefrom. This moves up and down each timeparallel to the standing surface of the container handling unit 1.

The two ends of the guiding cross-bars 10 a, 10 b are each guided in theU-shaped guide rail 20. This guide substantially reduces the twisting ofthe suspended spreader 17 relative to the support frame 3 and/or thecontainer 18.

FIG. 5 shows an alternative configuration of the lifting device 2 inperspective view from below. A hydraulic cylinder 4 firmly connected tothe support frame 3 is arranged underneath the support frame 3. Thepiston rod 5 of the hydraulic cylinder 4 is connected to a sliding piece24, which can travel in a linear guide 23. At the end of the slidingpiece 24 opposite the piston rod 5 are fastened four cable sheaths 25a-25 d, to which four cables 26, 27, 28, 29 are firmly connected. Thefour cable sheaths 25 are arranged in an imaginary rectangle, so thattwo cables 26, 27 are located in an upper level and two cables 28, 29 ina lower level. The two pairwise guided cables 26, 27 in the upper levelare deflected by two vertically pivoted deflection rollers 30, 31, eachgoing to one of the two corners of the forward support frame 3, fromwhich they are deflected by means of another two horizontally pivoteddeflection rollers 34, 35 into the vertical direction. It is not shownthat the cables 26, 27 are fastened to the upper ends of the tie bracket11 a and terminate there. Similar to the cables 26, 27 of the upperlevel, the cables 28, 29 of the lower level are deflected pairwise bymeans of two deflection rollers 32, 33, mounted on vertical pivot axes,so that they each run in the direction of one of the two corners of therear support frame 3. Here, the cables 28, 29 are deflected by means oftwo deflection rollers 36, 37 with horizontal pivot axes into thehorizontal direction. It is also not shown that the cables 28, 29 arefastened to the upper ends of the tie bracket 11 b and terminate there.

In this embodiment, there is no reeving of the cable 26-29, in order topreserve a compact design. The maximum stroke height of around 0.80 m,preferably 0.50 m, achieved in this way is sufficient for a plurality oftransport applications.

Similar to the embodiment described in FIG. 14, the guiding cross-bar 10a is arranged on the tie bracket 11 a and the guiding cross-bar 10 b onthe tie bracket 11 b. The spreader 17 is likewise fastened by means ofthe traction means 16 to the guiding cross-bars 10 a, 10 b.

The lengthwise movement of the piston rod 5 of the hydraulic cylinder 4is transformed by the deflected cables 26-29 into an up and downmovement of the guiding cross-bars 10 a and 10 b and, thus, that of theattached spreader 17.

The maximum stroke of the piston rod 5 corresponds to the distancebetween uppermost and lowermost end position of the spreader 17.

FIG. 6 shows a detailed view of the four deflection rollers 30-33arranged in an upper and lower level around horizontal pivot axes,including the four cables 26-29, the cable sheaths 15, and the slidingpiece 24.

LIST OF REFERENCE NUMBERS

-   1 Container handling unit-   2 Lifting device-   3 Support frame-   4 Hydraulic cylinder-   5 Piston rod-   6 Lever arm-   7 Angle lever-   8 Lever arm-   9 a, 9 b Vertical coupling rod-   10 a, 10 b Guiding cross-bar-   11 a, 11 b Tie bracket-   12 Horizontal coupling rod-   13 Lever arm-   14 Angle lever-   15 Lever arm-   16 Traction means-   17 Spreader-   18 Container-   19 Support pillar-   20 Guide rail-   21 Longitudinal beam-   22 Flange-   23 Linear guide-   24 Sliding piece-   25 a, 25 d Cable sheaths-   26-29 Cable-   30-33 Vertically mounted deflection roller-   34-37 Horizontally mounted deflection roller-   38, 39 Turning tube-   A Turning axis of angle lever 7-   B Turning axis of angle lever 14-   S Line of symmetry

1. A lifting device for containers which can be handled by means of container handling equipment, said lifting device comprising: at least one hydraulic cylinder arranged on a support frame with a piston and a piston rod, at least two horizontal guiding cross-bars spaced apart from each other, wherein lengthwise displacement of said piston rod is transformed into a synchronous upward and downward movement, said horizontal guiding cross-bars connected to a load-receiving device for the container, said horizontal guiding cross-bars being guided on vertical beams of the support frame at both ends, for the lifting and lowering of the container, wherein transformation of the lengthwise displacement of said piston rod into the upward and downward movement is accomplished by at least one angle lever pivoted on said support frame, said at least one angle lever comprising two lever arms, one of said lever arms being connected to said piston rod and the other of said lever arms being connected to one of said guiding cross-bars.
 2. The lifting device per claim 1, wherein said one of said lever arms connected to said piston rod is linked by a rod-shaped coupling element to a lever arm of another angle lever, whose other lever arm is connected to the other one of said guiding cross-bars, such that traction devices suspended from said guiding cross-bars move synchronously to each other in the vertical direction.
 3. The lifting device per claim 2, wherein each of said guiding cross-bars is connected by a coupling rod to one of said lever arms.
 4. The lifting device claim 3, wherein each of said guiding cross-bars is connected by a coupling rod to one of said lever arms on either side of the middle of the cross-bar.
 5. The lifting device per claim 4, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices.
 6. The lifting device per claim 1, wherein each of said guiding cross-bars is connected by a coupling rod to one of said lever arms.
 7. The lifting device per claim 6, wherein each of said guiding cross-bars is connected by a coupling rod to one of said lever arms on either side of the middle of the cross-bar.
 8. The lifting device per claim 7, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices.
 9. The lifting device per claim 2, wherein each of said guiding cross-bars is connected by a coupling rod to one of said lever arms on either side of the middle of the cross-bar.
 10. The lifting device per claim 9, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices.
 11. The lifting device per claim 1, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices.
 12. The lifting device per claim 2, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices.
 13. The lifting device per claim 3, wherein said load-receiving device for the container is suspended in the form of a spreader from said guiding cross-bars via traction devices. 